Reducing agent injection device, exhaust gas processing device and exhaust gas processing method

Abstract

Reducing agent injection device (100, 200), comprising: a honeycomb structure (1) comprising: a columnar honeycomb structure section (11) with a partition (15) defining several cells (14), each extending from a fluid inlet face (13a) to a fluid outlet face (13b); and at least one pair of electrode sections (12) configured to heat the honeycomb structure section (11) by passing a current, wherein the pair of electrode sections (12) is arranged on a side surface of the honeycomb structure section (11), wherein the honeycomb structure (1) is configured to decompose urea in an aqueous urea solution in the honeycomb structure section (11) heated by passing the current to produce ammonia; an outer cylinder (2) configured to accommodate the honeycomb structure (1), wherein the outer cylinder (2) has a carrier gas inlet opening (22) configured to introduce a carrier gas on the side of the fluid inlet end face (13a); a urea spray device (3) configured to spray the aqueous urea solution on the side of the fluid inlet face (13a) of the honeycomb structure section (11), wherein the urea spray device (3) is arranged at one end of the outer cylinder (2); a carrier gas inlet cylinder (4) provided at the carrier gas inlet opening (22) of the outer cylinder (2); and a carrier gas flow amplifier (5) configured to increase the flow rate of the carrier gas, wherein the carrier gas flow amplifier (5) is provided in the carrier gas inlet cylinder (4).

Description

AREA OF INVENTION

[0001] The present invention relates to a reducing agent injection device, an exhaust gas processing device and an exhaust gas processing method. BACKGROUND OF THE INVENTION

[0002] An exhaust gas processing device using a catalyst for the selective catalytic reduction of NOx (SCR catalyst) is known for cleaning nitrogen oxides (NOx) in exhaust gases emitted by various power engines (Patent Literature 1).

[0003] The exhaust gas processing device described in patent literature 1 includes a catalyst (SCR catalyst) attached to an exhaust pipe of an engine, and means for injecting urea water into the exhaust pipe between the engine and the catalyst, and also includes several urea water injection agents for mixing urea water with an exhaust gas, for reacting with specific components in the exhaust gas through the catalyst, and for mixing the urea water with the exhaust gas.

[0004] However, in the exhaust gas processing device described in patent literature 1, the exhaust gas temperature must be 200 °C or higher to decompose the urea in the urea water into ammonia using the heat of the exhaust gas. If the exhaust gas temperature is lower, the decomposition reaction is difficult to carry out, and the amount of ammonia required for NOx treatment is insufficient.

[0005] Therefore, an exhaust gas processing device using a reducing agent injection device has been proposed, wherein the reducing agent injection device comprises: a honeycomb structure (a honeycomb heating device) with a cylindrical honeycomb structure section and a pair of electrode sections arranged on a side face of the honeycomb structure section; and a urea spraying device configured to spray an aqueous urea solution onto the honeycomb structure section (Patent Reference 2). The reducing agent injection device used in the exhaust gas processing device can spray the aqueous urea solution onto the honeycomb structure section, which has been electrically heated by applying a voltage to the electrode sections, and decompose the urea in the aqueous urea solution within the honeycomb structure to efficiently produce ammonia.

[0006] However, spraying the aqueous urea solution onto the electrically heated honeycomb structure section causes a temperature decrease in the area where the aqueous urea solution is sprayed, creating a temperature irregularity within the honeycomb structure section. As a result, urea deposits (crystals caused by urea) tend to form in the area of ​​lower temperature within the honeycomb structure section. The formation of these urea deposits blocks a flow path within the honeycomb structure section, thus preventing the decomposition of the urea into ammonia.

[0007] Therefore, exhaust gas treatment devices have been proposed that utilize a reducing agent injection device equipped with a carrier gas inlet between the urea injection nozzle and the honeycomb structure (patent references 3 and 4). According to the reducing agent injection device used in each exhaust gas treatment device, a carrier gas introduced through the carrier gas inlet can promote gas flow within the honeycomb structure section. Therefore, even when the aqueous urea solution is sprayed onto the honeycomb structure section, a temperature difference within the section can be reduced, thus suppressing the formation of urea deposits. LIST OF COUNTERPOINTS Patent Literature [Patent Literature 1] Japanese patent application, Publication No. JP 2007 - 327 377 A [Patent literature 2] WO 2014 / 148506A1 [Patent Literature 3] Japanese patent application, Publication No. JP 2017 - 180 298 A [Patent Literature 4] Japanese patent application, Publication No. JP 2017 - 180 299 A SUMMARY OF THE INVENTION The problem to be solved by the invention

[0008] For the reducing agent injection devices described in patent literature 3, however, it can be difficult to introduce the carrier gas into the reducing agent injection device, depending on the types of carrier gases used and their positions. For example, if a gas (exhaust gas) from an engine exhaust system is used as the carrier gas, the exhaust gas pressure decreases depending on the position of the reducing agent injection device, making it difficult to introduce the exhaust gas from an exhaust pipe into the reducing agent injection device. In particular, if the pressure drop across the honeycomb structure is significant, the exhaust gas may not be able to flow from the exhaust pipe into the reducing agent injection device at all.A reduced amount of carrier gas introduced into the reducing agent injection device may not sufficiently promote the flow of gas in the honeycomb structure, so that urea deposits can easily be formed.

[0009] The present invention was made to solve the problems mentioned above. It is an object of the present invention to provide a reducing agent injection device that can stably suppress urea deposits.

[0010] Furthermore, it is another object of the present invention to provide an exhaust gas processing device and an exhaust gas processing method that can stably inject a required amount of ammonia from the reducing agent injection device in order to clean NOx. Means to solve the problem

[0011] As a result of intensive studies focusing on a method for introducing a carrier gas into a reducing agent injection device, the inventors of the present invention have found that, using a carrier gas flow amplifier, the carrier gas can be introduced stably into the reducing agent injection device regardless of the types of carrier gases used, thereby completing the present invention.

[0012] Therefore, the present invention relates to a reducing agent injection device comprising: a honeycomb structure that includes: a columnar honeycomb structure section with a partition defining several cells, each extending from a fluid inlet face to a fluid outlet face; and at least one pair of electrode sections configured to heat the honeycomb structure section by passing a current, wherein the pair of electrode sections is arranged on a side face of the honeycomb structure section, wherein the honeycomb structure is configured to decompose urea in an aqueous urea solution in the honeycomb structure section heated by passing the current to produce ammonia; an outer cylinder configured to accommodate the honeycomb structure, wherein the outer cylinder has a carrier gas inlet opening configured to introduce a carrier gas on the side of the fluid inlet end face; a urea spray device configured to spray the aqueous urea solution on the side of the fluid inlet end face of the honeycomb structure section, wherein the urea spray device is arranged at one end of the outer cylinder; a carrier gas inlet cylinder provided at the carrier gas inlet opening of the outer cylinder; and a carrier gas flow amplifier configured to increase the flow rate of the carrier gas, wherein the carrier gas flow amplifier is provided in the carrier gas inlet cylinder.

[0013] Furthermore, the present invention relates to an exhaust gas processing device comprising: an exhaust pipe through which exhaust gas flows; the reducing agent injection device, which is configured to inject ammonia into the exhaust line; and an SCR catalyst located on the exhaust cylinder on a downstream side of a position where the ammonia is injected.

[0014] Furthermore, the present invention relates to a method for processing an exhaust gas, wherein the method comprises injecting generated ammonia into the exhaust gas through the reducing agent injection device and reducing the exhaust gas mixed with the ammonia through an SCR catalyst. Effects of the invention

[0015] According to the present invention, it is possible to create a reducing agent injection device that can stably suppress urea deposits.

[0016] Furthermore, according to the present invention, it is possible to create an exhaust gas processing device and an exhaust gas processing method that can stably inject a required amount of ammonia from the reducing agent injection device in order to clean the NOx. BRIEF DESCRIPTION OF THE DRAWINGS Fig.Figure 1 is a schematic cross-sectional view showing a reducing agent injection device according to embodiment 1 of the present invention; Fig. Figure 2 is a schematic top view showing a fluid inlet end face of a honeycomb structure forming a reducing agent injection device according to embodiment 1 of the present invention; Fig. Figure 3 is a schematic cross-sectional view to explain a state in which a reducing agent injection device according to embodiment 1 of the present invention is provided in an exhaust pipe; Fig. Figure 4 is a schematic cross-sectional view to explain a further state in which a reducing agent injection device according to embodiment 1 of the present invention is provided in an exhaust pipe; Fig.Figure 5 is a schematic cross-sectional view showing a reducing agent injection device according to embodiment 2 of the present invention; Fig. Figure 6 is a schematic cross-sectional view showing an exhaust gas processing device according to embodiment 3 of the present invention; and Fig. Figure 7 is a schematic cross-sectional view showing an exhaust gas processing device according to embodiment 4 of the present invention. DETAILED DESCRIPTION OF THE INVENTION

[0017] Preferred embodiments of a reducing agent injection device, an exhaust gas processing device, and a method for processing exhaust gas according to the present invention are described in detail below with reference to the drawings. It should be understood that the present invention is not limited to the following embodiments, and that modifications, improvements, and the like added to the following embodiments based on the knowledge of a person skilled in the art, without departing from the inventive concept of the present invention, fall within the scope of protection of the present invention. For example, some components may be omitted from all components described in the embodiments, or components from different embodiments may be combined as appropriate. <Ausführungsform 1> (1) Reducing agent injection device

[0018] Fig.Figure 1 is a schematic cross-sectional view showing a reducing agent injection device according to embodiment 1 of the present invention (a schematic cross-sectional view parallel to an extension direction of cells of a honeycomb structure section).

[0019] As in Fig. Figure 1 shows a reducing agent injection device 100 according to the present embodiment: a honeycomb structure 1; an outer cylinder 2; a urea spray device 3; a carrier gas inlet cylinder 4; and a carrier gas flow amplifier 5.

[0020] The honeycomb structure 1 comprises: a columnar honeycomb section 11 with a partition 15 defining several cells 14 extending from a fluid inlet face 13a to a fluid outlet face 13b; and at least one pair of electrode sections 12 configured to heat the honeycomb section 11 by conducting a current, the electrode sections 12 being arranged on a side face of the honeycomb section 11. The cells 14 of the honeycomb section 11 form a flow path.

[0021] The “fluid inflow face 13a”, as used here, means a face with a fluid inflow opening, while the “fluid outflow face 13b” means a face with a fluid outflow opening. Furthermore, the “pair of electrode sections 12”, as used here, means that one electrode section 12 is arranged on a side opposite the other electrode section 12 above the center of the honeycomb structure section 11 in a cross-section orthogonal to the direction of extension of the cells 14 of the honeycomb structure section 11.

[0022] The electrode section 12 is formed in a band shape along the extension direction of the cells 14. A pair of electrode sections 12 is preferred, but pairs of electrode sections 12 are possible with regard to increasing the heat generation efficiency of the honeycomb structure section 11.

[0023] The outer cylinder 2 has an inlet-side end section and an outlet-side end section and houses the honeycomb structure 1 therein. The inlet-side end section, which is one end, is provided with the urea spray device 3, while the outlet-side end, which is the other end, is provided with an injection port 21 for injecting ammonia. Furthermore, the outer cylinder 2 has a carrier gas inlet port 22, which is configured to introduce a carrier gas on the side of the fluid inlet face 13a of the honeycomb structure section 11, i.e., between the honeycomb structure 1 and the urea spray device 3.

[0024] The honeycomb structure 1, housed within the outer cylinder 2, is secured (held) in the outer cylinder 2 by an insulating retaining section 23. This ensures insulation between the honeycomb structure 1 and the outer cylinder 2. There may be a section (space) where the insulating retaining section 23 is not located between the honeycomb structure 1 and the outer cylinder 2, but the entire outer circumference of the honeycomb structure 1 can be covered by the insulating retaining section 2. The material of the insulating retaining section 23 is not particularly restricted, as long as it exhibits excellent insulating properties. For example, aluminum oxide can be used.

[0025] The urea spray device 3 is arranged at one end (inlet-side end section) of the outer cylinder 2 and sprays an aqueous urea solution on the side of the fluid inlet face 13a of the honeycomb structure section 11. The aqueous urea solution is a starting material for ammonia, which is generated by the reducing agent injection device 100 according to the present embodiment.

[0026] The carrier gas inlet cylinder 4 is provided at the carrier gas inlet opening 22 of the outer cylinder 2. The other end of the carrier gas inlet cylinder 4 is connected to a supply source of a carrier gas, which is introduced into the carrier gas inlet cylinder 4.

[0027] Non-restrictive examples of the carrier gas that can be used include exhaust gases, intake gases, and air from other air supply devices (compressors and the like, fitted to large vehicles and the like). Exhaust gas is preferred. If, in addition, the intake gas (a gas from the intake system of an engine) is used as the carrier gas, it is preferred to preheat the intake gas using heating agents or the like, since the temperature of the intake gas is lower.

[0028] The carrier gas flow amplifier 5 has a function of increasing the flow rate of the carrier gas and is provided in the carrier gas inlet cylinder 4.

[0029] In the reducing agent injection device 100 according to the present embodiment, which has the structure described above, the urea in the aqueous urea solution sprayed by the urea spray device 3 is decomposed in the honeycomb structure section 11, which is heated by the flow of the current, to produce ammonia (a reducing agent), the ammonia being injected outwards via the injection port 21. In this case, introducing the carrier gas into the side of the fluid inlet face 13a of the honeycomb structure section 11 can cause the gas to flow from the fluid inlet face 13a to the side of the fluid outlet face 13b in the honeycomb structure section 11. Furthermore, depending on the types of carrier gases used, it can be difficult to introduce the carrier gas into the reducing agent injection device 100.However, because the carrier gas flow amplifier 5 is provided in the carrier gas inlet cylinder 4, the carrier gas can be introduced stably into the reducing agent injection device 100. Therefore, it is difficult for the heat and the aqueous urea solution to accumulate in the honeycomb structure section 11, thus stably suppressing urea deposits.

[0030] The reducing agent injection device 100 according to the present embodiment is described in detail below for each component. (1-1) Honeycomb structure 1

[0031] The honeycomb structure 1 contains the honeycomb structure section 11 and the electrode sections 12.

[0032] The partition 15, which forms the honeycomb structure section 11, may preferably be made of ceramic, although this is not particularly restricted. In particular, the partition 15 preferably comprises a silicon-silicon carbide composite material or silicon carbide as a major component, and more preferably a silicon-silicon carbide composite material as a major component. The use of such a material makes it possible to adjust the specific electrical resistance of the honeycomb structure section 11 to any desired value simply by changing the ratio of silicon carbide to silicon.

[0033] The term "silicon-silicon carbide composite material," as used herein, refers to a material containing silicon carbide particles as an aggregate and metallic silicon as a binder for binding the silicon carbide particles. Preferably, several silicon carbide particles are bound by metallic silicon in the silicon-silicon carbide composite material. Furthermore, "silicon carbide," as the main component, refers to a material formed by sintering silicon carbide particles. Additionally, the term "main component," as used herein, refers to a component present in an amount of 90% by weight or more.

[0034] The honeycomb structure section 11 preferably has a resistivity of 0.01 to 500 Ωcm and more preferably of 0.1 to 200 Ωc, although this is not a strict requirement. Controlling the resistivity to such a level can effectively heat the honeycomb structure section 11 by applying a voltage to at least one pair of electrode sections 12. In particular, to heat the honeycomb structure section 11 to 160 to 600 °C using a power source with a voltage of 12 to 200 V, the resistivity is preferably in the range mentioned above.

[0035] The specific electrical resistance of honeycomb structure section 11 is a value at 25 °C. The specific electrical resistance of honeycomb structure section 11 is a value measured using a four-terminal method.

[0036] The honeycomb structure section 11 preferably has an area per unit volume of 5 cm². 2 / cm 3 or larger and preferably from 8 to 45 cm 2 / cm 3 and especially preferred between 20 and 40 cm 2 / cm 3 The area of ​​5 cm 2 / cm 3 or larger can ensure that a sufficient contact area with the aqueous urea solution is maintained, thereby appropriately controlling the treatment rate of the aqueous urea solution, i.e., the amount of ammonia produced (a generation rate).

[0037] The area of ​​honeycomb structure section 11 is an area of ​​the surfaces of the partition wall 15 of honeycomb structure section 11.

[0038] The partition 15 of the honeycomb structure section 11 preferably has a thickness of 0.06 to 1.5 mm and more preferably of 0.10 to 0.80 mm. A partition thickness of 1.5 mm or less can reduce pressure loss, thereby appropriately controlling the treatment rate of the aqueous urea solution, i.e., the amount of ammonia produced (production rate). A partition thickness of 0.06 mm or greater can prevent the honeycomb structure section 11 from being destroyed by thermal shock caused by electrical conduction.

[0039] If the shape of each cell 14 (the shape of the cross-section orthogonal to the extension direction of cell 14) is circular, as in Fig. As shown in Figure 2, the thickness of the partition 15 represents the thickness of a section in which "a distance between the cells 14 is the shortest (a section in which the thickness of the partition 15 is less)".

[0040] The cells 14 preferably have a density of 7 to 140 cells / cm³. 2 and preferably 15 to 120 cells / cm² 2 The cell density is 14 out of 7 cells / cm³. 2 or more can ensure a sufficient contact area with the aqueous urea solution, thereby appropriately controlling the treatment rate of the aqueous urea solution, i.e., the amount of ammonia produced (production rate). The cell density is 14 out of 140 cells / cm². 2 or less can reduce the pressure loss, thereby appropriately controlling the treatment rate of the aqueous urea solution, i.e., the amount of ammonia produced (production rate).

[0041] The honeycomb structure section 11 can have several cells 14 which are provided with sealing sections at the end section on the side of the fluid inlet face 13a. The material of the sealing sections is preferably the same as that of the partition 15, although other materials can be used.

[0042] In addition to the one described in Fig. The square shape shown in Figure 2 can have various forms, such as a rectangle or other polygons, a circle, and an ellipse. Furthermore, the shape of the fluid inlet face 13a is the same as that of the fluid outlet face 13b and preferably orthogonal to the direction of extension of the cells 14, just like the shape of the cross-section.

[0043] The size of the honeycomb structure section 11 is such that the areas of the fluid inlet face surface 13a and the fluid outlet face surface 13b each range from 50 to 10000 mm². 2and preferably from 100 to 8000 mm 2 be.

[0044] The shape of each cell 14 in cross-section orthogonal to the extension direction of the cell 14 is in addition to that in Fig. The circular shape shown in Figure 2 is preferably an ellipse, a square, a hexagon, an octagon, or a combination thereof. Such a shape can reduce the pressure drop when the exhaust gas is passed through the honeycomb structure section 11, thereby efficiently decomposing the urea in the aqueous urea solution.

[0045] Each electrode section 12 is formed in a band shape along the extension direction of the cells 14, but may be formed with a wider width extending in the circumferential direction of the honeycomb structure section 11. Furthermore, in cross-section, one electrode section 12 is arranged orthogonally to the extension direction of the cells 14 on the opposite side of the other electrode section 12, with the center of the honeycomb structure section 11 positioned between them. Such a configuration can enable any bias of the current flowing in the honeycomb structure section 11 to be suppressed when the voltage is applied between the pair of electrode sections 12, thus suppressing the bias that generates heat in the honeycomb structure section 11.

[0046] Furthermore, applying the voltage to the electrode sections 12 preferably heats the honeycomb structure section 11, such that the temperature of the fluid inlet face 13a is 900 °C or lower. The temperature of the honeycomb structure section 11 can be directly controlled by providing temperature measuring devices directly on the honeycomb structure section 11. Alternatively, it is also possible to estimate and control the temperature of the honeycomb structure section 11 from the temperature of the carrier gas, the flow rate of the carrier gas, and the amount of aqueous urea solution sprayed. Furthermore, if the operating conditions of the engine are to be simulated, this simulation can be replaced by measuring the temperature and flow rate of the carrier gas.

[0047] The material of the electrode sections 12 is preferably the same as the main component of the partition 15 of the honeycomb structure section 11, although it is not particularly restricted to this.

[0048] The electrode sections 12 preferably have a specific electrical resistance of 0.0001 to 100 Ωcm and more preferably of 0.001 to 50 Ωcm. The specific electrical resistance of the electrode sections 12 in such a range allows the pair of electrode sections 12 to effectively act as electrodes in an exhaust gas line through which an exhaust gas at elevated temperature flows. The specific electrical resistance of the electrode sections 12 is preferably lower than that of the honeycomb structure section 11.

[0049] The specific electrical resistance of the electrode sections 12 is a value at 400 °C. The specific electrical resistance of the electrode sections 12 is a value that is measured by the four-terminal method.

[0050] The pair of electrode sections 12 can be provided with electrode connection projection sections 16 for connecting electrical wiring 18 from the outside. The material of the electrode connection projection sections 16 can be a conductive ceramic or a metal. Furthermore, the material of the electrode connection projection sections 16 is preferably the same as that of the electrode sections 12. It is also preferred that each electrode connection projection section 16 and a connector 17 of the outer cylinder 2 are connected by the electrical wiring 18.

[0051] The honeycomb structure section 11 can be equipped with a urea hydrolysis catalyst. Using the urea hydrolysis catalyst, ammonia can be efficiently produced from urea. Examples of urea hydrolysis catalysts include titanium oxide and the like. (1-2) External cylinder 2

[0052] The outer cylinder 2 is preferably made of stainless steel or the like, although this is not particularly restricted.

[0053] To adapt the outer cylinder 2 to the honeycomb structure 1, the outer cylinder 2 preferably has the same type of shape in cross-section, orthogonal to the direction of extension of the cells 14, as that of the honeycomb structure section 11. The term "same type of shape" used here means that if the shape of the outer cylinder 2 is square, the shape of the honeycomb structure section 11 is also square, while if the shape of the outer cylinder 2 is rectangular, the shape of the honeycomb structure section 11 is also rectangular. For example, if the shapes of the outer cylinder 2 and the honeycomb structure section 11 are of the same type and their shapes are rectangular, it is not necessary for both to have the same length-to-width ratio. (1-3) Urea spray device 3

[0054] The type of urea spray device 3 is not particularly restricted, as long as it can spray the aqueous urea solution. It is preferably a solenoid type, an ultrasonic type, a piezoelectric actuator type, or an atomizer type. Using these devices, the aqueous urea solution can be easily sprayed in the form of a mist. Furthermore, among these, the use of the solenoid, ultrasonic, or piezoelectric actuator type can enable the aqueous urea solution to be sprayed in the form of a mist without using air. This can eliminate the need to heat the air used to spray the aqueous urea solution, thereby reducing the amount of energy required for heating.Because the injection volume is reduced by not using the air for spraying, the speed at which the aqueous urea solution passes through the honeycomb structure section 11 in the form of a mist can also be reduced, resulting in a longer reaction time required for decomposition. The size (diameter) of each droplet of the aqueous urea solution sprayed by the urea spray device 3 is preferably 0.3 mm or less. If the droplet size is larger than 0.3 mm, it may be difficult to vaporize it when heated in the honeycomb structure section 11.

[0055] Here, the solenoid-type urea spray device 3 is a device that sprays the aqueous urea solution by oscillating the solenoid or by moving a piston back and forth through an electric field using the solenoid. Furthermore, the ultrasonic-type urea spray device 3 is a device that sprays the aqueous urea solution in the form of a mist by ultrasonic vibration. Additionally, the piezoelectric actuator-type urea spray device 3 is a device that sprays the aqueous urea solution in the form of a mist by oscillating a piezoelectric element. Moreover, the atomizer-type urea spray device 3 is, for example, a device that sprays the solution in the form of a mist by drawing the solution in through a tube and blowing the drawn-in solution out to the tip of the tube using air.The urea spray device 3 of the atomizer type can be a device in which several small openings are formed at the tip of the nozzle and the solution is sprayed out of the openings in the form of mist.

[0056] In the urea spray device 3, the spray direction (the direction in which the droplets are ejected) of the aqueous urea solution is preferably directed towards the side of the fluid inflow frontal surface 13a of the honeycomb structure section 11 in order to promote the spraying of the aqueous urea solution on the side of the fluid inflow frontal surface 13a of the honeycomb structure section 11. (1-4) Carrier gas inlet cylinder 4

[0057] The carrier gas inlet cylinder 4 may be made of any material that includes stainless steel and the like, but is not particularly restricted to that.

[0058] The shape of the carrier gas inlet cylinder 4 is not particularly restricted. It is preferred that its cross-sectional shape be of the same type as that of the carrier gas inlet cylinder 2 formed in the outer cylinder 2. Such a shape can facilitate the connection of the carrier gas inlet cylinder 4 with the carrier gas inlet opening 22.

[0059] When the exhaust gas is used as the carrier gas, as in Fig. As shown in Figure 3, it is preferred that the carrier gas inlet cylinder 4 branches off from an exhaust line 61 through which the exhaust gas flows. In such a configuration, a portion of the exhaust gas flowing through the exhaust line 61 can be easily directed into the carrier gas inlet cylinder 4.

[0060] Furthermore, the carrier gas inlet cylinder 4 preferably branches off from the exhaust gas line 61 on the downstream side of the position where the ammonia generated in the reducing agent injection device 100 is injected, as shown in Fig. Figure 4 shows this configuration. In such a configuration, the carrier gas heated in the reducing agent injection device 100 can be drawn back into the reducing agent injection device 100, thus improving the suppression of urea deposits. If the carrier gas is drawn from the downstream side of the position where the ammonia generated in the reducing agent injection device 100 is injected, the carrier gas can contain the ammonia, but the ammonia in the carrier gas passes directly through the reducing agent injection device 100, so that the function of the reducing agent injection device 100 is not affected. (1-5) Carrier gas flow amplifier 5

[0061] The carrier gas flow amplifier 5 is not particularly restricted, and various flow amplifiers, such as a Coanda flow amplifier, which utilizes a Coanda effect and an ejector, can be used. Such flow amplifiers are commercially available, including, for example, the Air Saver from TOHIN Co., Ltd., the AIR-X from TOEI KAISHA, LTD., a transvector, and a float transvector from KOGI CORPORATION. The Coanda flow amplifier, for example, can increase the flow rate of the carrier gas by 20 times or more than that of the ambient air by introducing outside air from an outside air inlet opening 51.

[0062] When the exhaust gas is used as the carrier gas, the carrier gas flow rate amplifier 5 preferably increases the exhaust gas flowing from the exhaust pipe into the carrier gas inlet cylinder 4 to a flow rate of 1.1 times or more. The upper limit of the flow rate amplification factor is not particularly restricted, although it may preferably be 1.8 times and more preferably 1.6 times. This amplification to such a flow rate can ensure that the carrier gas is adequately introduced into the reducing agent injection device 100.

[0063] Next, the method for manufacturing the reducing agent injection device 100 according to the present embodiment will be described in detail. (2) Method for manufacturing the reducing agent injection device 100(2-1) Production of the honeycomb structure 1

[0064] If the honeycomb structure 1 is made of ceramic, the method for producing the honeycomb structure 1 is preferably as follows: The process for producing the honeycomb structure 1 includes: a manufacturing step of a honeycomb preform; a manufacturing step of a dried honeycomb body; a manufacturing step of a honeycomb body with unfired electrodes and a manufacturing step of a honeycomb structure. (Manufacturing step of a honeycomb preform)

[0065] The step of producing a honeycomb mold preferably includes extruding a forming material to create the honeycomb mold. The forming material preferably comprises a ceramic starting material and an organic binder. In addition to the ceramic starting material and the organic binder, the forming material may further contain a surfactant, a sintering aid, a pore-forming agent, water, and the like. The forming material can be obtained by mixing these starting materials.

[0066] The ceramic starting material in the forming starting material is a "ceramic" or "a starting material that forms a ceramic upon firing." In either case, the ceramic starting material forms a ceramic after firing. The ceramic starting material in the forming starting material preferably contains metallic silicon and silicon carbide particles (silicon carbide powder) as the main components, or silicon carbide particles (silicon carbide powder) as one main component. This can provide the resulting honeycomb structure 1 with conductivity. The metallic silicon also preferably consists of metallic silicon particles (metallic silicon powder). The phrase "contains metallic silicon and silicon carbide particles as the main components" means that the total mass of the metallic silicon and the silicon carbide particles is 90% by mass or more of the whole (ceramic starting material).Examples of components other than the main components contained in the ceramic starting material include SiO2, SrCO3, Al2O3, MgCO3 and cordierite.

[0067] When silicon carbide is used as the main component of the ceramic starting material, it is sintered by firing. When metallic silicon and silicon carbide particles are used as the main components of the ceramic starting material, the silicon carbide particles are bonded together as an aggregate with the metallic silicon acting as a binder by firing.

[0068] When silicon carbide particles (the silicon carbide powder) and metal silicon particles (the metal silicon powder) are used as the ceramic starting materials, the mass of the metal silicon particles, based on the total mass of the silicon carbide and metal silicon particles, is preferably 10 to 40 wt%. The silicon carbide particles preferably have an average particle size of 10 to 50 µm and more preferably of 15 to 35 µm. The metal silicon particles preferably have an average particle size of 0.1 to 20 µm and more preferably of 1 to 10 µm. The average particle size of each of the silicon carbide and metal silicon particles is a value measured by a laser diffraction method.

[0069] Examples of organic binders include methylcellulose, glycerin, and hydroxypropylmethylcellulose. One type of organic binder or several types of organic binders can be used. The amount of organic binder added is preferably 5 to 10 parts by mass when the total mass of the ceramic starting materials is 100 parts by mass.

[0070] Ethylene glycol, dextrin, and the like can be used as the surfactant. One type of surfactant or several types of surfactants can be used. The amount of surfactant added is preferably 0.1 to 2.0 parts by mass when the total mass of the ceramic starting materials is 100 parts by mass.

[0071] The sintering aid that can be used contains SiO2, SrCO3, Al2O3, MgCO3, cordierite, and the like. One type of sintering aid or several types of sintering aids can be used. The amount of sintering aid added is preferably 0.1 to 3 parts by mass when the total mass of the ceramic starting materials is 100 parts by mass.

[0072] The pore-forming agent is not particularly restricted, as long as it forms pores after firing. Examples include graphite, starch, foamed resins, water-absorbing resins, and silica gel. One type of pore-forming agent or several types can be used. The amount of pore-forming agent added is preferably 0.5 to 10 parts by mass when the total mass of the ceramic starting materials is 100 parts by mass.

[0073] The amount of water added is preferably 20 to 60 parts by mass, when the total mass of the ceramic starting materials is 100 parts by mass.

[0074] When the forming material is extruded, it is first kneaded to form a green compact. The green compact is then extruded to obtain a honeycomb molded product. The honeycomb molded product has a porous partition 15 that defines the cells 14, each extending from the fluid inlet face 13a to the fluid outlet face 13b. The partition 15 of the honeycomb molded product is undried and unfired. (Manufacturing step of a dried honeycomb body)

[0075] In the step of producing a dried honeycomb core, the resulting honeycomb blank is first dried to create a dried honeycomb core. The drying conditions are not particularly restricted, and known conditions can be used. For example, it is preferred to dry the honeycomb blank for 0.5 to 5 hours at a temperature of 80 to 120 °C. (Manufacturing step of a honeycomb body with unburned electrodes)

[0076] In the manufacturing step of a honeycomb body with unfired electrodes, an electrode forming slurry containing the ceramic starting material and water is first applied to the side surface of the dried honeycomb body. The electrode forming slurry is then dried to form unfired electrodes and produce a honeycomb body with unfired electrodes.

[0077] For the honeycomb body with unheated electrodes, the dried honeycomb body is preferably provided with wide, rectangular, unheated electrodes, each extending in a band shape in the direction of extension of the cells 14 and also spreading in a circumferential direction. The circumferential direction refers to a direction along the side surface of the dried honeycomb body in cross-section orthogonal to the direction of extension of the cells 14.

[0078] The electrode formation slurry used in the manufacturing step of the honeycomb body with unfired electrodes contains a ceramic starting material and water. The electrode formation slurry may contain a surfactant, a pore-forming agent, water, and the like.

[0079] It is preferred to use the same ceramic starting material as that used in the production of the honeycomb preform. For example, if the main components of the ceramic starting material used in the production of the honeycomb preform are silicon carbide particles and metallic silicon, then the silicon carbide particles and metallic silicon can also be used as the ceramic starting materials of the electrode formation slurry.

[0080] There are no particular limitations on the method for applying the electrode formation slurry to the side surface of the dried honeycomb body. The electrode formation slurry can be applied, for example, using a brush or a pressure technique.

[0081] The electrode formation slurry preferably has a viscosity of 500 Pa·s or less, and more preferably of 10 to 200 Pa·s at 20 °C. A viscosity of 500 Pa·s or less allows for easy application of the electrode formation slurry to the side surface of the dried honeycomb body.

[0082] After applying the electrode formation slurry to the dried honeycomb body, the slurry can be dried to obtain unfired electrodes (the honeycomb body with unfired electrodes). The drying temperature preferably ranges from 80 to 120 °C. The drying time preferably ranges from 0.1 to 5 hours. (Manufacturing step of the honeycomb structure)

[0083] In the manufacturing step of a honeycomb structure, the honeycomb body is burned with the unburned electrodes to produce the honeycomb structure 1.

[0084] The firing conditions can be appropriately determined according to the types of ceramic starting material used in the production of the honeycomb preform and the ceramic starting material used in the electrode formation slurry.

[0085] Furthermore, calcination is preferably carried out after drying the honeycomb preform with the unfired electrodes and before firing, in order to remove the binder and the like. The calcination is preferably carried out in an air atmosphere at a temperature of 400 to 500 °C for 0.5 to 20 hours.

[0086] When the urea hydrolysis catalyst 40 is mounted on the honeycomb structure 1, the honeycomb structure 1 can, for example, be immersed in a container in which a slurry of the urea hydrolysis catalyst 40 is stored. By adjusting the viscosity of the slurry of the urea hydrolysis catalyst 40, the particle size of the contained urea hydrolysis catalyst 40, and the like, the catalyst can be mounted not only on the surfaces of the partition 15 but also in the pores of the partition 15, and the amount of catalyst to be mounted can also be adjusted. Furthermore, the amount of catalyst to be mounted can also be adjusted by repeatedly drawing up the slurry. (2-2) Production of the reducing agent injection device 100

[0087] The reducing agent injection device 100 can be manufactured by inserting the honeycomb structure 1 into the outer cylinder 2, securing the honeycomb structure 1 in the outer cylinder 2 via the insulation retaining section 23, arranging the urea spray device 3 at one end (inlet-side end section) of the outer cylinder 2, connecting each of the connectors 17 of the outer cylinder 2 to each of the electrode connection projection sections 16 arranged on the pair of electrode sections 12 via the electrical wiring 18, connecting the carrier gas inlet cylinder 4 to the carrier gas inlet opening 22 of the outer cylinder 2, and providing the carrier gas inlet cylinder 4 with the carrier gas flow amplifier 5.

[0088] Next, a method for using the reducing agent injection device 100 of the present embodiment will be described in detail. (3) Method for using the reducing agent injection device 100

[0089] The reducing agent injection device 100 according to the present embodiment supplies the aqueous urea solution as a starting material, whereby the urea in the aqueous urea solution is decomposed to produce ammonia, and the produced ammonia is injected externally. More specifically, the flow is passed through the honeycomb structure section 11 to increase the temperature (heating), the aqueous urea solution is supplied to the urea spray device 3, and the aqueous urea solution is sprayed from the urea spray device 3 towards the side of the fluid inlet face 13a of the honeycomb structure section 11.In this case, the flow of the aqueous urea solution is promoted by introducing the carrier gas at an increased flow rate through the carrier gas flow amplifier 5 via the carrier gas inlet opening 22 to the side of the fluid inlet face 13a of the honeycomb structure section 11, in order to prevent the aqueous urea solution from stagnating in the honeycomb structure section 11. The aqueous urea solution sprayed from the urea spray device 3 is heated and evaporates as it passes through the honeycomb structure section 11. Due to the increased pressure in the area between the honeycomb structure section 11 and the urea spray device 3, caused by the evaporation of the aqueous urea solution, and due to the flow of the carrier gas, the aqueous urea solution sprayed by the urea spray device 3 enters the cells 14 of the honeycomb structure section 11 from the fluid inlet face 13a.The urea in the aqueous urea solution supplied to the cells 14 is decomposed by the temperature of the heated honeycomb structure section 11 to produce the ammonia.

[0090] The flow rate of the carrier gas after amplification by the carrier gas flow rate amplifier 5 can preferably be from 1 to 200 l / min and more preferably from 2 to 50 l / min, although it is not specifically limited to this range. Such a flow rate can lead to efficient introduction of the carrier gas into the honeycomb structure section 11.

[0091] The amount of aqueous urea solution supplied is not particularly limited, and may preferably range from 1.0 to 2.0 in an equivalent ratio to the amount of nitrogen oxides (NOx) contained in the exhaust gas. If the equivalent ratio is less than 1.0, the amount of nitrogen oxides emitted without purification may increase. However, if the SCR catalyst is equipped with a NOx storage function, there may be a period during which the equivalent ratio is less than 1.0. If the equivalent ratio is greater than 2.0, there is a risk that the exhaust gas will likely be emitted with the ammonia mixed into it.

[0092] The aqueous urea solution is preferably an aqueous solution containing 10 to 40 wt% urea, although this is not particularly restricted. If the urea content is less than 10 wt%, it is necessary to spray a large quantity of the aqueous urea solution to reduce NOx, which may increase the amount of electrical power required to conduct the current to heat the honeycomb structure section 11. If the urea content is greater than 40 wt%, there is concern that the urea may solidify in cold areas. Preferred examples of the aqueous urea solution include AdBlue (an aqueous solution containing 32.5 wt% urea; a registered trademark of the German Association of the Automotive Industry (VDA)), which is widely available on the market.

[0093] The heating temperature of the honeycomb structure section 11 is preferably 160 °C or higher, more preferably 160 to 600 °C, and even more preferably 250 to 400 °C. A heating temperature of 160 °C or higher can lead to easy and efficient decomposition of the urea. A heating temperature of 600 °C or lower can allow the ammonia to be burned off and prevent it from being fed into the exhaust gas line. Furthermore, it is preferred that the heating temperature of the honeycomb structure section 11 be 360 ​​°C or higher, because sulfur compounds, such as ammonium hydrogen sulfate and ammonium sulfate, which precipitate on the reducing agent injection device 100, can be removed.

[0094] The maximum voltage applied to the honeycomb structure section 11 preferably ranges from 12 to 200 V, more preferably from 12 to 100 V, and even more preferably from 12 to 48 V. A maximum voltage of 12 V or higher allows for easy temperature increase of the honeycomb structure section 11. A maximum voltage of 200 V or lower avoids the need for an expensive voltage-increasing device. <Ausführungsform 2>

[0095] Fig. Figure 5 is a schematic cross-sectional view showing a reducing agent injection device according to embodiment 2 of the present invention (a schematic cross-sectional view parallel to an extension direction of the cells of a honeycomb structure section).

[0096] As in Fig.As shown in Figure 5, a reducing agent injection device 200 according to the present embodiment has a different configuration than that of the reducing agent injection device 100 according to embodiment 1 in that the former further includes a urea hydrolysis catalyst body 31 on the side of the fluid outlet face 13b of the honeycomb structure section 11, which is spaced apart from the fluid outlet face 13b. The other configurations of the reducing agent injection device 200 according to the present embodiment are the same as those of the reducing agent injection device 100 according to embodiment 1. Therefore, the descriptions of the other configurations are omitted, and only the differences are described in detail.

[0097] In the reducing agent injection device 200 according to the present embodiment, the urea hydrolysis catalyst body 31, which is spaced apart from the fluid outlet face 13b, is provided on the side of the fluid outlet face 13b of the honeycomb structure section 11. In such a configuration, unreacted urea in the honeycomb structure section 11 can be decomposed into ammonia by the urea hydrolysis catalyst body 31, thus increasing the efficiency of ammonia production.

[0098] The urea hydrolysis catalyst body 31 is preferably a honeycomb structure on which a urea hydrolysis catalyst is supported. A support (honeycomb structure) used for the urea hydrolysis catalyst body 31 can have the same structure and material as that of the upstream honeycomb structure 1. The honeycomb structure used for the urea hydrolysis catalyst body 31 may not have a pair of electrode sections 12, but it can be configured to be heated by an electrical conductor as in the upstream honeycomb structure 1.

[0099] After the honeycomb structure (support) has been fabricated, the urea hydrolysis catalyst body 31 can support the urea hydrolysis catalyst on the honeycomb structure as in the upstream honeycomb structure 1. The method for supporting the urea hydrolysis catalyst on the honeycomb structure is as described above. <Ausführungsform 3>

[0100] The Fig. 6 and Fig. Figure 7 are schematic cross-sectional views showing exhaust gas processing devices according to embodiment 3 of the present invention.

[0101] As in the Fig. 6 and Fig. As shown in Figure 7, each of the exhaust gas processing devices 300, 400 according to the present embodiment comprises: an exhaust gas line 61 through which the exhaust gas flows; the reducing agent injection device 100 for injecting the ammonia into the exhaust gas line 61; and an SCR catalyst 62, which is arranged on the exhaust gas line 61 on a downstream side of a position where the ammonia is injected.

[0102] The exhaust pipe 61 is a tube through which exhaust gas (an exhaust gas containing NOx) emitted by various engines and the like is routed and in which the exhaust gas and ammonia are mixed. The size of the exhaust pipe 61 is not particularly limited and can be suitably determined depending on the exhaust systems, such as the engines to which the exhaust gas treatment devices 300, 400 are attached according to the present embodiment. The exhaust pipe 61 has a non-restrictive length in the direction of gas flow, but preferably a length at which a suitable distance between the reducing agent injection device 100 and the SCR catalyst 62 can be set.

[0103] The material for the exhaust pipe 61 is not particularly restricted, although a material that is difficult to corrode due to the exhaust gas is preferred. Examples of materials for the exhaust pipe 61 include stainless steel and the like.

[0104] If the exhaust gas is used as the carrier gas to be introduced into the reducing agent injection device 100, the carrier gas inlet cylinder 4 is connected such that it branches off from the exhaust gas line 61, as shown in the Fig. 6 and Fig.Figure 7 shows the position of the carrier gas inlet cylinder 4 branching off from the exhaust line 61, either upstream or downstream of the reducing agent injection device 100. By arranging the carrier gas inlet cylinder 4 downstream of the reducing agent injection device 100, the carrier gas heated in the reducing agent injection device 100 can be drawn back into the reducing agent injection device 100, thus improving the suppression of urea deposits.

[0105] If a carrier gas other than the exhaust gas (e.g. the inlet gas) is used, the carrier gas inlet cylinder 4 is further connected to a supply source for the carrier gas.

[0106] The reducing agent injection device 100 has an injection port 21 in the exhaust gas line 61, which injects the ammonia into the exhaust gas line 61. By injecting the ammonia into the exhaust gas line 61 from the reducing agent injection device 100, a mixed gas of ammonia and exhaust gas is produced in the exhaust gas line 61.

[0107] As in Fig. As shown in Figure 6, a reducing agent injection device 100 can be attached to the exhaust pipe 61. As shown in Fig.As shown in Figure 7, two reducing agent injection devices can also be attached to the exhaust pipe 61. In this case, the reducing agent injection device on the downstream side can be the reducing agent injection device 100 or a conventional reducing agent injection device 500 (e.g., the urea spray device 3), which sprays the reducing agent (urea water) without heating. In a preferred embodiment, the reducing agent injection device on the downstream side is the conventional reducing agent injection device 500, which sprays the reducing agent (urea water) without heating.This is because, when the NOx content in the exhaust gas is lower (when the exhaust gas temperature is lower), most of the NOx is removed by the reducing agent injection device 100 and the SCR catalyst 62 on the upstream side, whereas, when the NOx content in the exhaust gas is higher (when the exhaust gas temperature is higher), the urea solution sprayed by the conventional reducing agent injection device 500 is decomposed into ammonia by the exhaust gas temperature. Furthermore, although not shown, three or more reducing agent injection devices 100 can be fitted to the exhaust pipe 61 as required.

[0108] The SCR catalyst 62, in the form of a catalyst body (the honeycomb structure on which the SCR catalyst 62 is supported), is located on the exhaust line 61 downstream of the position where the ammonia is injected. Therefore, as shown in Fig.As shown in Figure 6, the SCR catalyst 62 is arranged on the exhaust pipe 61 on the downstream side of the position where the reducing agent injection device 100 is located, if one reducing agent injection device 100 is located on the exhaust pipe 61. If two reducing agent injection devices 100 are located on the exhaust pipe 61, the SCR catalysts 62 are arranged on the exhaust pipe 61 on the downstream side of the positions where the reducing agent injection device 100 and the conventional reducing agent injection device 500 are located, respectively, as shown in Figure 6. Fig. 7 is shown.

[0109] The examples of SCR catalyst 62 include vanadium-based catalysts and zeolite-based catalysts.

[0110] When the SCR catalyst 62 is used as a catalyst body that is supported on the honeycomb structure, it is preferred that the catalyst body is contained in a container and that the container is attached to the exhaust pipe 61 on the downstream side.

[0111] The honeycomb structure supporting the SCR catalyst 62 is not particularly restricted, and honeycomb structures known in the art can be used.

[0112] It is preferred that a filter for capturing suspended particles in the exhaust gas is arranged on the upstream side of the exhaust pipe 61. Examples of filters for capturing suspended particles include, for example, a ceramic DPF (diesel particulate filter) 63 having a honeycomb structure. Furthermore, it is preferred that an oxidation catalyst 64 for removing hydrocarbons and carbon monoxide from the exhaust gas is arranged on the upstream side of the exhaust pipe 61. The oxidation catalyst 64 is preferably in a state in which it is supported on a ceramic honeycomb structure (oxidation catalyst). Preferred examples of the oxidation catalyst 64 that can be used contain precious metals, such as platinum (Pt), palladium (Pd), and rhodium (Rh).

[0113] When a reducing agent injection device 100 is attached to the exhaust pipe 61, the DPF 63 and the oxidation catalyst 64 are arranged on the exhaust pipe 61 on the upstream side of the position where the ammonia is injected by the reducing agent injection device 100, as shown in Fig. Figure 6 shows that, when two reducing agent injection devices 100 are attached to the exhaust pipe 61, the DPF 63 and the oxidation catalyst 64 are arranged on the exhaust pipe 61 on the upstream side of the position where the ammonia is injected by the conventional reducing agent injection device 500, and on the downstream side of the SCR catalyst 62 at the position where the reducing agent injection device 100 is attached, as shown in Figure 6. Fig. 7 is shown.

[0114] It is preferred to arrange an ammonia removal catalyst (oxidation catalyst) on the downstream side of the SCR catalyst 62 for the removal of ammonia. Such an arrangement can prevent ammonia from being emitted externally when excess ammonia, which has not been used for NOx removal in the exhaust gas, flows to the downstream side. Preferred examples of the oxidation catalyst arranged on the downstream side of the SCR catalyst 62 contain precious metals, such as platinum (Pt), palladium (Pd), and rhodium (Rh).

[0115] The above description describes the use of the reducing agent injection device 100 of embodiment 1. However, the reducing agent injection device 200 of embodiment 2 can also be used. <Ausführungsform 4>

[0116] In a process for processing exhaust gas according to embodiment 4 of the present invention, the ammonia generated in the reducing agent injection device 100, 200 according to embodiment 1 or 2 is injected into the exhaust gas, and the exhaust gas mixed with the ammonia is reduced by the SCR catalyst. Consequently, the NOx in the exhaust gas can be removed. The process for processing the exhaust gas can be easily carried out using the exhaust gas processing device 300, 400 according to embodiment 3.

[0117] The reducing agent injection device 100, 200 can supply the carrier gas, together with the aqueous urea solution sprayed by the urea spray device 3, to the side of the fluid inlet face 13a of the honeycomb structure section 11 at a flow rate increased by the carrier gas flow amplifier 5. This promotes sufficient gas flow in the honeycomb structure section 11, preventing urea from remaining there and thus increasing the production limit of urea deposits. Furthermore, the ammonia decomposed by heating can be expelled to the outside by the carrier gas, thereby improving reactivity.

[0118] The temperature and flow rate of the carrier gas and the power supplied to the honeycomb structure 1 are preferably set such that the temperature of the fluid inlet face 13a of the honeycomb structure section 11 is 150 °C or higher, and preferably 250 °C or higher. To achieve such temperature control, for example, the temperature of the carrier gas is preferably 180 °C or higher, and the flow rate is preferably 10 l / min or greater. The power supplied to the honeycomb structure 1 preferably ranges from 150 to 500 W.

[0119] The amount of ammonia injected by the reducing agent injection device 100, 200 is preferably between 1.0 and 2.0 in an equivalent ratio to the amount of nitrogen oxides contained in the exhaust gas. If the equivalent ratio is less than 1.0, the amount of nitrogen oxides emitted without purification may increase. If the equivalent ratio is greater than 2.0, there is a risk that the exhaust gas will likely be emitted with the ammonia mixed into it.

[0120] It is preferred that the sprayed quantity of the aqueous urea solution and the temperature (power supply) of the honeycomb structure section 11 are controlled by an electronic control unit. Furthermore, the temperature can be calculated from a resistance value of the honeycomb structure section 11, whereby the temperature of the honeycomb structure section 11 can be controlled so that the calculated temperature is a setpoint temperature. EXAMPLES

[0121] The present invention is described in more detail below with regard to examples. However, the present invention is not limited to these examples. (Example 1)

[0122] The in Fig. The reducing agent injection device 100 shown was manufactured according to the following procedure: First, silicon carbide (SiC) powder and metallic silicon (Si) powder were mixed in a 70:30 mass ratio to produce a ceramic starting material. Hydroxypropyl methylcellulose was added to the ceramic starting material as a binder, and a water-absorbing resin was added as a pore-forming agent. Further water was added to produce a shaping starting material. The shaping starting material was kneaded using a vacuum green compact kneader to produce a green compact. The amount of binder added was 7 parts by mass of 100 parts by mass of the ceramic starting material. The amount of pore-forming agent added was 3 parts by mass of 100 parts by mass of the ceramic starting material. The amount of water added was 42 parts by mass of 100 parts by mass of the ceramic starting material.The average particle size of the silicon carbide powder was 20 µm, while the average particle size of the metallic silicon powder was 6 µm. The average particle size of the pore-forming agent was also 20 µm. The average particle size of each of the silicon carbide, metallic silicon, and pore-forming agent was measured using a laser diffraction method.

[0123] The resulting green compact was formed using an extrusion machine to obtain a honeycomb mold with a square column shape (a column shape with a square cross-section orthogonal to the cell orientation). The resulting honeycomb mold was dried by dielectric high-frequency heating and then dried for 2 hours at 120 °C using a hot air dryer, with both end faces trimmed by a predetermined amount.

[0124] Subsequently, silicon carbide (SiC) powder and metallic silicon (Si) powder were mixed in a mass ratio of 60:40 to prepare an electrode-forming ceramic starting material. To this starting material, hydroxypropyl methylcellulose was added as a binder, glycerol as a humectant, and a surfactant as a dispersant, along with water. The mixture was then kneaded to obtain an electrode-forming slurry.

[0125] The electrode formation slurry was then applied in a strip shape to two parallel surfaces on the side of the dried honeycomb blank (dried honeycomb body). Specifically, the electrode formation slurry was applied in a strip shape to one of the four flat surfaces (four side faces) of the dried honeycomb body and to a side parallel to the surface where the slurry was applied. The shape (outer circumference) of the electrode formation slurry applied to the side of the dried honeycomb body was rectangular.

[0126] The electrode-forming slurry applied to the dried honeycomb core was then dried to obtain a honeycomb core with unfired electrodes. The drying temperature was 70 °C.

[0127] Two electrode connection protrusion sections 16 were produced separately using the same materials as those of the electrode formation slurry.

[0128] The two electrode connection protrusion sections 16 were each attached to two electrode sections of the honeycomb body with the unburned electrodes. The honeycomb body with the unburned electrodes was degreased, burned, and further oxidized to obtain the honeycomb structure 1. The degreasing conditions were 550 °C for 3 hours. The burning conditions were 1450 °C for 2 hours in an argon atmosphere. The oxidation conditions were 1300 °C for 1 hour.

[0129] The thickness of the partition 15 of the honeycomb structure 1, obtained as described above, was 0.152 mm, while the cell spacing was 1.11 mm. The area of ​​the honeycomb structure section 11 per unit volume was 31.1 cm². 2 / cm 3The honeycomb structure 1 had a columnar shape with square end faces, one side of which was 30 mm. Furthermore, the length of the cells 14 of the honeycomb structure 1 was 25 mm in the longitudinal direction. The specific electrical resistance of the electrode sections was 0.1 Ωcm, while the specific electrical resistance of the honeycomb structure section 11 was 1.4 Ωcm. No sealing section was formed on the honeycomb structure 1.

[0130] The outer cylinder 2 was then manufactured from stainless steel. A connector 17 for the electrical wiring was attached to the outer circumference of the outer cylinder 2. The honeycomb structure 1 was inserted into the outer cylinder 2 and secured by the insulation retaining section 23. One of the electrode connection projection sections 16 of the honeycomb structure 1 was connected to the connector 17 of the outer cylinder 2 via the electrical wiring 18. Furthermore, the other electrode connection projection section 16 was brought into contact with the outer cylinder 2.Furthermore, the solenoid-type urea spray device 3 was arranged in the inlet-side end section of the outer cylinder 2, wherein the carrier gas inlet cylinder 4 made of stainless steel was connected to the carrier gas inlet opening 22 of the outer cylinder 2, wherein the carrier gas inlet cylinder 4 was provided with the TOHIN air saver as the carrier gas flow amplifier 5 to obtain the reducing agent injection device 100. (Comparative example 1)

[0131] A reducing agent injection device was obtained in the same procedure as that of Example 1, except that the carrier gas flow amplifier 5 was not provided.

[0132] The reducing agent injection device obtained in the above example was installed at a predetermined position in the exhaust pipe, as shown in Fig.Figure 3 shows a test performed by changing the amplification factor of the exhaust gas flow rate through the carrier gas flow rate amplifier 5 and continuously spraying a constant quantity of an aqueous urea solution (AdBlue) for 30 minutes to determine a maximum spray rate (g / min) of the aqueous urea solution when no urea deposit was generated on the fluid inlet face of the honeycomb structure. Additionally, for the reducing agent injection device obtained in the comparison example above, the maximum spray rate (g / min) of the aqueous urea solution when no urea deposit was generated on the fluid inlet face of the honeycomb structure section was determined using the same procedure as described above. The results are shown in Table 1. The presence or absence of urea deposits was visually assessed. [Table 1] Amplification factor of the exhaust gas flow rate (Male) Increased exhaust gas flow rate (l / min) Maximum spray volume of aqueous urea solution (g / min) Comparative example 1 1,00 0 1,0 Example 1 1,05 1 1,5 1,10 10 4,2 1,20 30 4,8 1,30 50 3,7 1,60 80 3,0 1,80 100 2,0

[0133] As shown in Table 1, it was found that the reducing agent spray device equipped with the carrier gas flow amplifier 5, as in the example, exhibited a higher maximum spray volume of the aqueous urea solution when no urea deposit was generated on the fluid inlet face of the honeycomb structure section than the reducing agent spray device not equipped with the carrier gas flow amplifier 5, as in the comparison example, where the former was able to stably suppress the urea deposits. In particular, when the amplification factor of the exhaust gas flow rate by the carrier gas flow amplifier 5 was set to 1.10 times or more, the maximum spray volume of the aqueous urea solution was higher when no urea deposit was generated on the fluid inlet face of the honeycomb structure.

[0134] As can be seen from the results above, it is possible according to the present invention to provide a reducing agent injection device that can stably suppress urea deposits. Furthermore, it is possible according to the present invention to provide an exhaust gas processing device and an exhaust gas processing method that can stably inject a required amount of ammonia from the reducing agent injection device to clean NOx. Industrial applicability

[0135] The reducing agent injection device, the exhaust gas processing device and the method for processing the exhaust gas according to the present invention can be suitablely used to clean the NOx in the exhaust gases emitted by various power engines and the like. DESCRIPTION OF REFERENCE MARKS 1 honeycomb structure 2 external cylinders 3 Urea spray device 4 carrier gas inlet cylinders 5 Carrier gas flow amplifiers 11 honeycomb structure section 12 Electrode section 13a Fluid inlet face area 13b Fluid outlet face area 14 cells 15 partition wall 16 Electrode connection protrusion section 17 connectors 18 Electrical wiring 21 Injection port 22 Carrier gas inlet opening 23 Insulation holding section 31 Urea hydrolysis catalyst bodies 51 Outside air inlet opening 61 Exhaust pipe 62 SCR catalyst 63 DPF 64 Oxidation catalyst 100, 200 Reducing agent injection device 300, 400 exhaust gas processing device 500 conventional reducing agent injection devices

Claims

Reducing agent injection device (100, 200) comprising: a honeycomb structure (1) comprising: a columnar honeycomb structure section (11) with a partition (15) defining multiple cells (14), each extending from a fluid inlet end face (13a) to a fluid outlet end face (13b); and at least one pair of electrode sections (12) configured to heat the honeycomb structure section (11) by passing an electric current, the pair of electrode sections (12) being arranged on a side face of the honeycomb structure section (11), the honeycomb structure (1) being configured to decompose urea in an aqueous urea solution in the honeycomb structure section (11) heated by passing the electric current to produce ammonia;an outer cylinder (2) configured to accommodate the honeycomb structure (1), the outer cylinder (2) having a carrier gas inlet opening (22) configured to introduce a carrier gas on the side of the fluid inlet end face (13a); a urea spray device (3) configured to spray the aqueous urea solution on the side of the fluid inlet end face (13a) of the honeycomb structure section (11), the urea spray device (3) being located at one end of the outer cylinder (2); a carrier gas inlet cylinder (4) provided at the carrier gas inlet opening (22) of the outer cylinder (2); and a carrier gas flow amplifier (5) configured to increase the flow rate of the carrier gas, the carrier gas flow amplifier (5) being provided in the carrier gas inlet cylinder (4). Reducing agent injection device (100, 200) according to claim 1, wherein the carrier gas is an exhaust gas and the carrier gas inlet cylinder (4) branches off from an exhaust gas line (61) through which the exhaust gas flows. Reducing agent injection device (100, 200) according to claim 2, wherein the carrier gas inlet cylinder (4) branches off from the exhaust line (61) on a downstream side of a position where ammonia is sprayed. Reducing agent injection device (100, 200) according to claim 2 or 3, wherein the carrier gas flow rate amplifier (5) increases the exhaust gas flowing from the exhaust gas line (61) into the carrier gas inlet cylinder (4) to a flow rate of 1.1 times or more. Reducing agent injection device (100, 200) according to one of claims 1 to 4, which further comprises a urea hydrolysis catalyst body (31) which is arranged on the side of the fluid outflow end face (13a) of the honeycomb structure section (11), wherein the urea hydrolysis catalyst body (31) is spaced apart from the fluid outflow end face (13a). Reducing agent injection device (100, 200) according to one of claims 1 to 5, wherein the honeycomb structure section (11) has a specific electrical resistance of 0.01 to 500 Ωcm. Reducing agent injection device (100, 200) according to one of claims 1 to 6, wherein the honeycomb structure section (11) contains a silicon-silicon carbide composite material or silicon carbide as a main component. Reducing agent injection device (100, 200) according to one of claims 1 to 7, wherein the honeycomb structure section (11) has an area per unit volume of 5 cm2 / cm3 or more. Exhaust gas processing device comprising: an exhaust gas line (61) through which an exhaust gas flows; the reducing agent injection device (100, 200) according to any one of claims 1 to 8, configured to inject ammonia into the exhaust gas line (61); and an SCR catalyst (62) arranged on the exhaust gas cylinder on a downstream side of a position where the ammonia is injected. Method for processing an exhaust gas, wherein the method comprises injecting generated ammonia into the exhaust gas through the reducing agent injection device (100, 200) according to one of claims 1 to 8 and reducing the exhaust gas mixed with the ammonia through an SCR catalyst (62).

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